Color image processing
First Claim
1. A method of performing a colour transformation or colour retouch operation on multibit digital data defining P colour components of image pixels in which N most significant bits (MSBs) of each colour component value address a look-up table (LUT) containing coarse versions of output pixel colour component values, and M least significant bits (LSBs) of each colour component value are used to interpolate fine versions of the output pixel values from the coarse output pixel values, wherein P, N, and M are integers and wherein in a first step, for each colour the 2NP addresses of the LUT are loaded with appropriate coarse output pixel values, and in a second step the input pixel data addresses the LUT to obtain coarse output pixel data which is subsequently interpolated, and wherein the first and second steps are repeated with increasing values of N.
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Abstract
Apparatus for performing a color transformation or color retouch operation on multibit digital data defining P color components of image pixels. The apparatus comprises a look-up table (2) which is addressed by N most significant bits (MSBS) of each color component value and which contains coarse versions of output pixel color component values. An interpolator (3) is responsive to M least significant bits (LSBS) of each color component value to interpolate fine versions of the output pixel values from the coarse output pixel values obtained from the look-up table. A processor loads coarse output pixel data for each color component into the 2NP addresses of the look-up table which may be addressed by the M MSBs of the input pixel data. The processor (8) is adapted to cause the value of N progressively to increase with successive iterations.
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Citations
10 Claims
- 1. A method of performing a colour transformation or colour retouch operation on multibit digital data defining P colour components of image pixels in which N most significant bits (MSBs) of each colour component value address a look-up table (LUT) containing coarse versions of output pixel colour component values, and M least significant bits (LSBs) of each colour component value are used to interpolate fine versions of the output pixel values from the coarse output pixel values, wherein P, N, and M are integers and wherein in a first step, for each colour the 2NP addresses of the LUT are loaded with appropriate coarse output pixel values, and in a second step the input pixel data addresses the LUT to obtain coarse output pixel data which is subsequently interpolated, and wherein the first and second steps are repeated with increasing values of N.
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9. Apparatus for performing a colour transformation or colour retouch operation on multibit digital data defining P colour components of image pixels, the apparatus comprising a look-up table which is addressed by N most significant bits (MSBs) of each colour component value and which contains coarse versions of output pixel colour component values;
- interpolation means responsive to M least significant bits (LSBs) of each colour component value to interpolate fine versions of the output pixel values from said coarse output pixel values obtained from said look-up table; and
control means for loading coarse output pixel data for each colour component into the 2NP addresses of said look-up table which may be addressed by the N MSBs of the input pixel data, wherein P, N, and M are integers and wherein said control means is adapted to cause the value of N progressively to increase with successive iterations. - View Dependent Claims (10)
- interpolation means responsive to M least significant bits (LSBs) of each colour component value to interpolate fine versions of the output pixel values from said coarse output pixel values obtained from said look-up table; and
Specification